Dredger



G. ZAPF DREDGER Aug. 1, 1933.

Filed Nov. 28, 1930 Patented Aug l, 1933 H PATENTIOFFICE DREDGER Georg Za'pf, Cologne, Germany, assignor to Felten & Guilleaume Carlswerk Actien-Gesellschaft,

Cologne-Mnlheim, Germany Application November 28, 1930, Serial No. 498,862,

andin Germany December 3, 1929 r 3 Claims. (Cl. 37 117) In many rope-driven dredgers, more particularly those used in lignite pits, a single rope is used for operating the bucket during the dredging and for moving the bucket backwards and forwards over the ground. Owing to the entirely different operating conditions existing during dredging and during the movement of the bucket over the ground, it has been found necessary to divide the drive of the rope in such dredgers into a dredging drive and a traversing drive. For this purpose separatedriving drums are as a rule provided for the two different modes of driving, said drums being driven by separate motors. 3 3

Such a dredger isillustrated diagrammatically in the accompanying drawing in Figs. 1 and 2. In the drawing, e is the dredging rope which serves for moving the bucket 0 over the ground and for moving it during the dredging operation, a is the driving drum for driving the rope during the dredging and b, b are the traversing driving pulleys for causing the load carrier to travel to and fro along the runway. The pulleys forguiding the rope e are marked d, d, f, f, y, y. In the drawing these pulleys, which are indicated by double reference letters (b, b, d, d and so on) are not shown juxtaposed but in tandem relation thereto for the sake of clearness. For changing the direction of the rope where it is guided over the traversing'driving pulleys b and b, the rope is guided from the pulley b to the pulley b over the counter or tensioning pulleys h. Theends of the rope e guided over these pulleys are both wound a number of times in opposite directions round the dredging driving drum (1 and thenfixed to the drum. During the dredging operation and during its backward and forward movement over the ground, the bucket 0 travels on the rollers p upon the supporting cable 0 which, extends along over the path of travelof the bucket the cable 0 being provided in theusual way with means for raising and lowering it according to whether the bucket is to be traversed at a slight distance above the ground or to be caused to dig into the ground. The means for raising and lowering the cable 0 is accomplished through the medium of the drum qand any well known means may be employed for tilting the bucket for dredging.

In Fig. l the arrows 7' indicate the direction of motion of the rope when traversing the bucket 0 along the path shown by the arrow over the ground. In this operation one of the traversing driving pulleys b, b is driven while the drum a (for dredging) is stationary. In the direction of the arrows 8 indicates the direction of motion of the rope eduringdredging. In this operation, the drum (1. is driven andone end of the rope s is wound up on the drum a While the other end. of the rope is unwoundhAs the bucket, during dredging, meets with considerable resistance dur-' ing this movement, the traversing driving pulleys b, b (which serve for operating the ropee duringthe traversing of the load over the ground) must be held stationaryby being braked, so. as to enable the desired movement of the bucket to. take place. On the driving pulleys b, b being put into operation to drive the rope e for travers ing the bucket above the-ground, the dredging drum a will have to remain stationary. Separate braking means for the drum a will as'a rule be" unnecessary, since for the backward and forward traverse of the bucket over'the ground consider.- ably .less power is nccessary than'for dredging and consequently the heavy dredging .drum can 7 remain at rest, even :without being specially braked for the purpose. r In the hitherto usual arrangements of this kind, it hasbeen found to be a disadvantage that when the bucket c is being operated fordredging, the rope slips over the driving pulleys b, b which are held stationary by brakes, owing to the amount of friction of the rope on the saidpulleys being too small. It has therefore been proposed. to prevent the rope slipping over the pulleys b, b and h when dredging by clamping the rope by means of a clamping device (1/, shown in broken lines in the drawing). Such braking by clamping the rope may, however, be very detrimental to the rope.

According to the present invention, in order to prevent slipping of the rope during the dredging operation, overthe traversing pulleys b, b',, which are held stationary when dredging, the opposed pulleys h. are iournalled so as'to be displaceable and raised by means of a piston is movable in the cylinder Zthrough the intermediary of a piston rod m, whereby the portion of the rope in question is tensioned. The piston is in the cylinder l is actuated preferably hydraulically but it may be operated pneumatically or otherwise. In this manner the sag of the rope can be varied by the" displacement of the opposed pulley h. The

this that the rope for producing the traversing motion is guided over a greater number of driving pulleys b, b and tensioning pulleys h for giving the rope a greater bearing surface, so that the friction thus increased by coiling the rope a number of times round braked pulleys will suffice, when the driving drum a for dredging is put in operation, for preventing the rope slipping over the stationary driving pulleys of the traversing means.

In certain cases a combination of the two above proposals may be used with advantage, in which an increased number of tensioning pulleys is provided which are raised by one of the lifting means referred to above for the purpose or" altering the tensioning in the rope.

The two last proposals: The employment of a greater number of tensioning pulleys and driving above the ground, a single traversing rope for the bucket, guide pulleys for saidtraversing rope, aodriving drum for operating the traversing rope for dredging, driving pulleys for operating the traversing rope to move the bucket over the ground, said driving pulleys being intended to be braked during dredging, the combination with atensioning pulley for said driving pulleys with the traversing rope passed round the tensioning pulley in its passage from one driving pulley to the other, of means for preventing slipping of the traversing rope during the operation of the driving drum for operating the rope for dredging,

said means comprising mechanical displacing.

means in engagement with the shaft of the tensioning pulley for varying the tension in the rope. 2. In a cable dredger having a bucket and a supporting cable therefor intended to be lowered during dredging so as to enable the bucket to remove the material to be dredged, and to be raised, so as to enable the bucket to be traversed above the ground, a single traversing rope for the bucket, guide pulleys for said traversing rope, a driving drum for operating the traversing rope ior'dredging, driving pulleys for operating the traversing rope to move the bucket over the ground, said driving pulleys being intended to be braked, during dredging, the combination with a tensioning pulleyfor said driving. pulleys with the traversing rope passed round the tensioning pulley in its passage from one driving pulley to the other, of means for preventing'slippin'g of the traversing rope during the operation of the driving drum for operating the rope for dredging, said means comprising hydraulically operated mechanical displacing means in engagement with the shaft of the tensioning pulley for varying the tension in the rope.

3. In a cable dredger havinga bucket and a,

supporting cable therefor intended to be lowered during dredging so as to enable the bucket to remove the material to be dredged, and to be raised, so as to enable the bucket to be traversed above the ground, a single traversing rope for the bucket, guide pulleys for said traversingrope,

a driving drum for operating the traversing rope for dredging, driving pulleys for operating the traversing rope to move the bucket over the ground, said driving pulleys, being intended to v be braked during dredging, a plurality of tensioning pulleys for said driving pulleys with the traversing rope passed round the tensioning pulleys in its passage from one driving pulley to the other so as to increase the bearing surface of the rope on the pulleys and prevent slipping of the rope during the operation of the driving drum for operating the rope for dredging.

' GEORG ZAPF. 

